Hysteretical temperature dependence of AC susceptibility in granular high-Tc superconductors

V. BEKERIS, H. FERRARI, C. ACHA, P. LEVY, G. POLLA, G. LEYVA

PHYSICA C - SUPERCONDUTIVITY

ELSEVIER SCIENCE BV

Lugar: New York; Año: 1994 vol. 234 p. 49 - 56

0921-4534

AbstractThe AC susceptibility, χAC(T), with superimposed DC magnetic field, HDSa, has been measured as a function of temperature in bulk sintered LaSrCuO, for zero-field cooled (ZFC) and field-cooled (FC) samples. Results are analyzed within Kim's critical-state model extended to a granular superconductor, where the role of grains is to determine the temperature-dependent effective permeability, μeff(T), and the effective intergranular local field, Heffj(HDCa, T), which depends on the applied field, HDCa and the thermal and magnetic history, accounting for the observed hysteresis. A method to determine field-independent intergranular critical-state parameters (critical current at zero field and temperature-dependent density of pinning forces as well as μeff(T)) and the proper scaling of Heffj(HDCa, T) for ZFC and FC conditions is described. The calculated AC susceptibility for the whole temperature range for both magnetic conditions reproduces the main features of the experimental results.